The present invention relates to a probe for a magnetic remanence measurement method, in particular for detecting deposits of foreign material and inclusions in hollow spaces, the hollow spaces being formed in a non-ferromagnetic material, and the foreign material deposits and inclusions being made of a ferromagnetic material, and the probe having at least one magnetic field sensor. The present invention further relates to a method for detecting foreign material deposits and inclusions in hollow spaces, the hollow spaces being formed in a non-ferromagnetic material, and the foreign material deposits and inclusions being made of a ferromagnetic material.
In a large number of technical applications, significant problems are caused by ferromagnetic inclusions situated in a non-ferromagnetic surrounding environment. Thus, for example, the smallest foreign material deposits or inclusions in components of aircraft engines can cause significant damage to these engines. Corresponding foreign material deposits and inclusions can be, for example, cutting material residue resulting from breakage or chipping of cutting edges of drilling tools. Such inclusions result in defects in the area of the surface of the corresponding components, but these defects are not easily recognizable. These foreign material deposits and inclusions become particularly relevant in the case of drilled holes, because these have an increased level of tension and are also very difficult to access. In order to detect foreign material deposits and inclusions in hollow spaces, in particular in bores in turbines and compressor materials of aircraft engines, destruction-free test methods based on ferromagnetism have been described. These methods are applicable because the materials spalled by the drilling tool are ferromagnetic hard metal, whereas turbine and compressor materials are not ferromagnetic. In particular, the magnetic remanence method, and also the eddy current method, have been described and used for the detection of small ferromagnetic particles in a non-ferromagnetic environment. However, these two methods have various disadvantages when used for the detection, location, and characterization of ferromagnetic inclusions in hollow spaces. Thus, up to now it has been possible to carry out the magnetic remanence method for the detection of foreign material deposits and inclusions only from the surface of the component. On the other hand, hollow space tests using the eddy current method have the disadvantage that it is possible to distinguish ferromagnetic inclusions from geometric anomalies only to a limited extent.
Therefore, the object of the present invention is to provide a probe of the general type described for a magnetic remanence measurement method that enables reliable detection and location of ferromagnetic foreign material deposits and inclusions in hollow spaces.
In addition, the object of the present invention is to provide a method of the general type described for the detection of foreign material deposits and inclusions in hollow spaces that ensures a reliable detection and location of ferromagnetic foreign material deposits and inclusions.